Air cooled brake assembly

ABSTRACT

A wheel brake assembly comprising a wheel detachably mounted on an axle, a brake assembly disposed between the wheel rim and the axle, and an air impeller carried by and rotatably supported or a support member carried by the wheel, the arrangement being such that when the wheel and support member are assembled on the axle the impeller is rotatably drivable through a friction drive mechanism to pass a current of air through the brake assembly. Of which the following is a specification.

United States Patent [191 Buckley [45] May 22, 1973 [75] Inventor:Stanley G. Buckley, Erdington, Bir- UNITED STATES N S mingham 24,England 2,822,997 2/1958 Du Bois ..l88/264 A X [73] Asslgneez DunlopHoldings Limited, London, 3,335,834 8/1967 Wach ..l88/264 A X EnglandPrimary Examiner-Richard A. Schacher [22] Filed 1971 Attorney-Richard K.Stevens et al. [21] Appl. No.: 200,351

[57] ABSTRACT [30] Foreign Application Priority Dat A wheel brakeassembly comprising a wheel detachably mounted on an axle, a brakeassembly Nov. 25, 1970 Great Britain ..S6,002/70 disposed between thewheei rim and the axle and an air impeller carried by and rotatablysupported or a support member carried by the wheel, the arrange- [52]US. Cl. ..l88/264 A ment being such that when the wheel and support [5..F16d member are a sembled on the axle the impeller is Fleld of SearchR, A, rotatably drivable through a friction drive mechanism 188/264 AAto pass a current of air through the brake assembly. Of which thefollowing is a specification.

11 Claims, 2 Drawing Figures Patented May 22, 1973 3,734,247

2 Sheets-Sheet 1 AIR COOLED BRAKE ASSEMBLY This invention relates to aircooled wheel and brake assemblies and particularly, though notexclusively, to air cooled wheel and brake assemblies for aircraft.

As an aircraft lands and the brakes are applied, kinetic energy isconverted into heat in the brake assembly. In the case of heavy aircrafthaving high landing speeds the rise in temperature of the wheel andbrake assembly which results from the heat build-up may be particularlyhigh and, unless checked, can cause distortion of the wheel and brakediscs, damage to the tires, and can unduly delay the turn round time ofthe aircraft.

In previously proposed wheel and brake assemblies, such as thatdescribed in the specification of our U.K. Pat. No. 943,472, a fan isarranged at the axially outer end of a wheel axle to draw air throughthe annular space between the wheel rim and wheel axle and therebyextract heat from the brake. This substantially increases the coolingrate of the brake and thereby prevents excessive temperature rises.

In order for the fan to pass sufficient air through the wheel and brakeassembly the outer diameter of the fan impeller needs to be greater thanthe diameter of the wheel axle. Thus the relatively large diameterimpeller prevents the direct removal of the wheel from the axle, and itis necessary to disassemble the impeller from the fan assembly beforethe wheel may be axially withdrawn in a conventional manner.

A further disadvantage of the currently used construction in which theimpeller prevents direct removal of the wheel is that the blades of theimpeller are rendered liable to damage very time that a wheel isremoved.

It is one object of the present invention to provide an improved fanassembly for use in conjunction with wheel and brake assemblies.

According to one aspect of the present invention a wheel and brakeassembly comprises a wheel detachably mounted on an axle, a brakeassembly disposed between the wheel rim and the axle, a support membercarried by the wheel, and an air impeller carried by and rotatablysupported on the support member, the arrangement being such that whenthe wheel and support member are assembled on the axle the impeller isrotatably drivable through a friction drive mechanism by a driving motorto pass a current of air through the brake assembly.

According to a further aspect of the present invention a wheel and brakeassembly comprises a wheel detachably mounted on an axle, a brakeassembly disposed between the wheel rim and the axle, a support membercarried by the wheel, and an air impeller carried by and rotatablysupported by the support member, the arrangement being such that whenthe wheel and support are assembled on the axle the impeller isrotatably drivable through a friction drive mechanism by a driving motorto pass a current of air through the brake assembly, a second driveshaft extending rotatably through the driving motor and engaging thesupport member to rotate therewith.

The second shaft may be used to drive a wheel speed sensor, and thesensor and driving motor may conveniently be housed in an in-lineconfiguration within a hollow axle.

One particular embodiment of the invention will now be described by wayof example with reference to the accompanying drawings in which:

FIG. 1 is a longitudinal sectional view through a wheel and brakeassembly in accordance with the present invention, and

FIG. 2 is a detailed sectional view of the friction clutch shown in FIG.1.

A wheel rim 10, of an aircraft wheel and brake assembly incorporating asensor 11 for an anti-skid braking system, is formed of two axiallyseparable parts 12,13 secured together by bolts 14 and rotatablysupported by bearings 15 on a relatively fixed hollow axle 16 secured toan oleo leg (not shown). An annular torque member 17 is secured by bolts18 to a sleeve 19 fixed on to the axle 16 and is formed with splines 20on which are slidably mounted stator brake discs 21. Corresponding rotorbrake discs 22 are mounted to slide on splines 23 on the wheel rim l0and are interleaved with the stator discs, layers of friction material24 being attached to the stator discs so as to be interposed betweenadjacent rotor and stator discs. A number of brake cylinders 25 aredisposed in a circle around the axle, and on admission of fluid underpressure to the cylinders, the assembly of brake discs 21,22 with theintervening layers of friction material 24 is compressed axially againstan annular reaction member 26 at one end of the stack of discs.

In operation the brake may be cooled by drawing air, by means of animpeller 27, through the brake assembly, through apertures 28 in the webportion 29 of the wheel, and through a duct 30 in the form of an annularfrusto-conical shield fixed to the wheel adjacent the rim portion byscrews 31. The air emerges through a grating 32 secured to the axiallyoutermost end of the shield.

The impeller 27 is provided at its center with an axially extendingannular hub portion 33 (see FIG. 2) rotatably mounted by a pair of lowfriction bearings 34 on a hollow impeller support tube 35 fastened tothe grating 32 and extending coaxially towards the interior of thehollow axle. A spacer 36 maintains the bearings in spaced axialrelationship between a pair of shoulders provided on the hub portion 33by a circlip 37 and an annular stop member 38 screwed into the axiallyinnermost end 39 of the impeller hub 33 in the same sense as thedirection of rotation of the driving motor. The impeller and bearingassembly is retained on the support tube 35, against a shoulder 40formed thereon, by means of another circlip 41. The impeller assembly isthus rotatably attached to the axially inner side of the grating 32 bymeans of the impeller support tube, and the axis of rotation of theassembled impeller on the grating is aligned with the axis of rotationof the wheel.

The impeller is drivable by an electric motor 42 located in a tubularsupport housing 43 within the hollow wheel axle 16. The motor isprovided with a tubular drive shaft 44 to which a friction clutch 45 isfitted for the transmission of drive from the motor to the impeller.

The friction clutch comprises a thrust member 46, and a pressure member47 which is rotatable by the motor and which is urged against a reactionsurface 48 on the axially inner end 39 of the impeller hub by means of acylindrical helical compression spring 49.

The thrust member 46 is in the form of a cylindrical tube 50 which fitsover the motor drive shaft 44 and is provided with a radially outwardlyprojecting annular lip 51 at its axially inner end to support theaxially inner end of the compression spring. Axial location of thethrust member on the drive shaft is provided by a radially inwardlyprojecting annular lip 52 formed at the axially outer end of the thrustmember, and extending over the end of the motor drive shaft. A tubularretaining bolt 53 is screwed axially into the end of the drive shaft 44to clamp the aforementioned lip 52 between the bolt head and the end ofthe motor drive shaft.

The pressure member 47 comprises a cylindrical portion 54 slidablymounted on the thrust member, and an axially outer portion 55 offrusto-conical shape which tapers from the end of the cylindricalportion. The frusto-conical portions acts as a clutch friction surfaceand is urged against a corresponding friction surface on the impellerhub by means of the compression spring 49 acting on an outwardlyextending lip 56 formed at the base of the frusto-conical portion of thepressure member. The corresponding friction surface on the impeller hubis formed on the conical face of the annular stop member 38 which isscrewed into the inner end of the impeller hub.

To limit axial movement of the pressure member 47 outwardly from thethrust member 46 under the action of the spring when the impellerassembly is removed from the wheel, a longitudinal slot 57 is providedin the cylindrical portion 54 of the pressure member and accommodatesthe head portion of a set screw 58 screwed radially into the thrustmember. The radially inner end of the set screw extends into alongitudinal groove 59 formed on the surface of the motor drive shaftand thereby secures the clutch assembly and motor drive shaft againstrelative rotation.

A wheel speed sensor 11 forming part of an anti-skid braking system ismounted within the tubular support housing 43, axially inwardly from themotor 42 and grating 32. To transmit the rotation of the wheel to thesensor a sensor drive shaft 60 extends coaxially and relativelyrotatably through the electric motor and friction clutch 45. The shaftis splined at each end to engage corresponding splines formed on the endof the input shaft 61 of the sensor and within the impeller support tube35. Thus, in the arrangement of this embodiment, the use of a hollowmotor drive shaft 44 in conjunction with the type of clutch describedpermits a compact arrangement of a wheel speed sensor and an electricmotor within a hollow wheel axle.

The impeller has radially extending fan blades 62 which induce air toflow over the brake discs as described, and also has internal vanes 63(see FIG. 2) which cause a current of air to flow through the hollowaxle l6 and apertured support housing 43 for the purpose of cooling themotor and sensor. A particular advantage of the embodiment describedabove is that by retaining the impeller within the shield the fan bladesare substantially protected from accidental damage whenever the wheel isdisassembled from the axle.

While in the embodiment described, the coupling between the motor andimpeller is in the form of a conical friction clutch, it is to beunderstood that the use of alternative frictional coupling means such asa plate clutch lies within the scope of the present invention. Likewise,various designs of shield and grating assemblies are known to personsskilled in the art, and may be used as an alternative to the integralshield and grating design described to support the impeller assembly.

Having now described my invention what I claim is:

l. A wheel and brake assembly comprising a wheel detachably mounted onan axle, a brake assembly disposed between the wheel rim and the axle, asupport member carried by the wheel, and an air impeller carried by androtatably supported on the support member, the arrangement being suchthat when the wheel and support member are assembled on the axle theimpeller is rotatably drivable through a friction drive mechanism by adriving motor to pass a current of air through the brake assembly.

2. A wheel and brake assembly according to claim 1 wherein the frictiondrive mechanism comprises a friction clutch having a pair of frictionsurfaces for springloaded engagement with each other.

3. A wheel and brake assembly according to claim 2 wherein the frictionclutch comprises a first friction surface provided on a hub portion ofthe air impeller, and a second friction surface provided on a pressuremember associated with the drive shaft of the driving motor so as torotate with the drive shaft of the motor, the pressure member beingspring-loaded axially relative to the drive shaft.

4. A wheel and brake assembly according to claim 3 wherein the impelleris rotatably supported on the support member by means of at least onelow-friction bearing located within the hub portion of the impeller, theimpeller being secured against axial movement in one direction relativeto the support member by means of an annular stop member secured withinthe axially inner end of the hub portion, a surface of the annular stopmember constituting the first friction surface of the friction clutch.

5. A wheel and brake assembly according to claim 2 wherein the frictionclutch is a conical clutch comprising a pair of substantiallyconical-shaped friction surfaces.

6. A wheel and brake assembly according to claim 1 wherein the supportmember comprises a grating through which a current of air may be inducedby the impeller to provide cooling for the brake assembly.

7. A wheel and brake assembly according to claim 1 wherein the supportmember comprises a duct in the form of a frusto-conical shield anddefines the radially outer boundary of an air passage between theimpeller and the brake assembly.

8. A wheel and brake assembly according to claim 1 wherein a seconddrive shaft extends rotatably through the driving motor and engages thesupport member to rotate therewith.

9. A wheel and brake assembly according to claim 8 wherein the seconddrive shaft is arranged to transmit rotation of the support member to awheel speed sensor mounted coaxially with the driving motor within theaxle of the wheel and brake assembly.

10. A wheel and brake assembly according to claim 9 wherein the driveshaft of the driving motor is tubular and the friction drive mechanismis provided with a central passage coaxial with the motor drive shaft topermit the second drive shaft to extend through the driving motor andfriction drive mechanism, one end of the second drive shaft engaging theimpeller support member to rotate therewith and the other end of thesecond drive shaft being associated with the wheel speed sensor totransmit rotation of the wheel thereto.

11. A wheel and brake assembly according to claim 9 wherein the wheelspeed sensor and driving motor are secured relative to one anotherwithin a tubular support housing locatable in the axle of the wheel andbrake assembly.

1. A wheel and brake assembly comprising a wheel detachably mounted onan axle, a brake assembly disposed between the wheel rim and the axle, asupport member carried by the wheel, and an air impeller carried by androtatably supported on the support member, the arrangement being suchthat when the wheel and support member are assembled on the axle theimpeller is rotatably drivable through a friction drive mechanism by adriving motor to pass a current of air through the brake assembly.
 2. Awheel and brake assembly according to claim 1 wherein the friction drivemechanism comprises a friction clutch having a pair of friction surfacesfor spring-loaded engagement with each other.
 3. A wheel and brakeassembly according to claim 2 wherein the friction clutch comprises afirst friction surface provided on a hub portion of the air impeller,and a second friction surface provided on a pressure member associatedwith the drive shaft of the driving motor so as to rotate with the driveshaft of the motor, the pressure member being spring-loaded axiallyrelative to the drive shaft.
 4. A wheel and brake assembly according toclaim 3 wherein the impeller is rotatably supported on the supportmember by means of at least one low-friction bearing located within thehub portion of the impeller, the impeller being secured against axialmovement in one direction relative to the support member by means of anannular stop member secured within the axially inner end of the hubportion, a surface of the annular stop member constituting the firstfriction surface of the friction clutch.
 5. A wheel and brake assemblyaccording to claim 2 wherein the friction clutch is a conical clutchcomprising a pair of substantially conical-shaped friction surfaces. 6.A wheel and brake assembly according to claim 1 wherein the supportmember comprises a grating through which a current of air may be inducedby the impeller to provide cooling for the brake assembly.
 7. A wheeland brake assembly according to claim 1 wherein the support membercomprises a duct in the form of a frusto-conical shield and defines theradially outer boundary of an air passage between the impeller and thebrake assembly.
 8. A wheel and brake assembly according to claim 1wherein a second drive shaft extends rotatably through the driving motorand engages the support member to rotate therewith.
 9. A wheel and brakeassembly according to claim 8 wherein the second drive shaft is arrangedto transmit rotation of the support member to a wheel speed sensormounted coaxially with the driving motor within the axle of the wheeland brake assembly.
 10. A wheel and brake assembly according to claim 9wherein the drive shaft of the driving motor is tubular and the frictiondrive mechanism is provided with a central passage coaxial with themotor drive shaft to permit the second drive shaft to extend through thedriving motor and friction drive mechanism, one end of the second driveshaft engaging the impeller support member to rotate therewith and theother end of the second drive shaft being associated with the wheelspeed sensor to transmit rotation of the wheel thereto.
 11. A wheel andbrake assembly according to claim 9 wherein the wheel speed sensor anddriving motor are secured relative to one another within a tubularsupport housing locatable in the axle of the wheel and brake assembly.